What data is missing?
Population growth? Aside from being pretty obvious anecdotally, the Pew report has data on it.
Age gap? You’re right. No studies, but I’ll go with what my eyes tell me, that the starting age for shidduchim has a 3-4 year spread, and most marriages follow suit.
Disparity of older singles? I’m maskim to not accept anecdotal evidence alone on that, it’s reasonable to suggest that there would be a perception bias there. I’m not maskim to dismiss the fact that the first two (growth and gap) lead to a disparity, it is pretty simple math, and experts have confirmed that.
Ela mai? Girls go otd more than boys? 10-12% more boys are born than girls? 8-10% of girls are marrying chsssidishe boys? It’s my weakest link, I’m maskim, but these are all highly counterintuitive (or in the case if birth ratio, against census studies).